/*
 * rtp.c
 *
 * library functions for the real-time transport protocol
 *
 * David A. McGrew
 * Cisco Systems, Inc.
 */

#include "rtp_priv.h"

#include <stdio.h>
#include <string.h>

#include <sys/types.h>
#ifdef HAVE_SYS_SOCKET_H
# include <sys/socket.h>
#endif

#define PRINT_DEBUG    0    /* set to 1 to print out debugging data */
#define VERBOSE_DEBUG  0    /* set to 1 to print out more data      */

unsigned int rtp_sendto(rtp_sender_t sender, const void* msg, int len) {
    int octets_sent;
    err_status_t stat;
    int pkt_len = len + RTP_HEADER_LEN;

    /* marshal data */
    strncpy(sender->message.body, msg, len);

    /* update header */
    sender->message.header.seq = ntohs(sender->message.header.seq) + 1;
    sender->message.header.seq = htons(sender->message.header.seq);
    sender->message.header.ts = ntohl(sender->message.header.ts) + 1;
    sender->message.header.ts = htonl(sender->message.header.ts);

    /* apply srtp */
    stat = srtp_protect(sender->srtp_ctx, &sender->message.header, &pkt_len);
    if (stat) {
#if PRINT_DEBUG
        fprintf(stderr, "error: srtp protection failed with code %d\n", stat);
#endif
        return -1;
    }
#if VERBOSE_DEBUG
    srtp_print_packet(&sender->message.header, pkt_len);
#endif
    octets_sent = sendto(sender->socket, (void*) &sender->message, pkt_len, 0,
            (struct sockaddr *) &sender->addr, sizeof(struct sockaddr_in));

    if (octets_sent != pkt_len) {
#if PRINT_DEBUG
        fprintf(stderr, "error: couldn't send message %s", (char *)msg);
        perror("");
#endif
    }

    return octets_sent;
}

unsigned int rtp_recvfrom(rtp_receiver_t receiver, void *msg, int *len) {
    int octets_recvd;
    err_status_t stat;

    octets_recvd = recvfrom(receiver->socket, (void *) &receiver->message,
            *len, 0, (struct sockaddr *) NULL, 0);

    /* verify rtp header */
    if (receiver->message.header.version != 2) {
        *len = 0;
        return -1;
    }

#if PRINT_DEBUG
    fprintf(stderr, "%d octets received from SSRC %u\n",
            octets_recvd, receiver->message.header.ssrc);
#endif
#if VERBOSE_DEBUG
    srtp_print_packet(&receiver->message.header, octets_recvd);
#endif

    /* apply srtp */
    stat = srtp_unprotect(receiver->srtp_ctx, &receiver->message.header,
            &octets_recvd);
    if (stat) {
        fprintf(stderr, "error: srtp unprotection failed with code %d%s\n",
                stat, stat == err_status_replay_fail ? " (replay check failed)"
                        : stat == err_status_auth_fail ? " (auth check failed)"
                                : "");
        return -1;
    }
    strncpy(msg, receiver->message.body, octets_recvd);

    return octets_recvd;
}

int rtp_sender_init(rtp_sender_t sender, int socket, struct sockaddr_in addr,
        unsigned int ssrc) {

    /* set header values */
    sender->message.header.ssrc = htonl(ssrc);
    sender->message.header.ts = 0;
    sender->message.header.seq = (uint16_t) rand();
    sender->message.header.m = 0;
    sender->message.header.pt = 0x1;
    sender->message.header.version = 2;
    sender->message.header.p = 0;
    sender->message.header.x = 0;
    sender->message.header.cc = 0;

    /* set other stuff */
    sender->socket = socket;
    sender->addr = addr;

    return 0;
}

int rtp_receiver_init(rtp_receiver_t rcvr, int socket, struct sockaddr_in addr,
        unsigned int ssrc) {

    /* set header values */
    rcvr->message.header.ssrc = htonl(ssrc);
    rcvr->message.header.ts = 0;
    rcvr->message.header.seq = 0;
    rcvr->message.header.m = 0;
    rcvr->message.header.pt = 0x1;
    rcvr->message.header.version = 2;
    rcvr->message.header.p = 0;
    rcvr->message.header.x = 0;
    rcvr->message.header.cc = 0;

    /* set other stuff */
    rcvr->socket = socket;
    rcvr->addr = addr;

    return 0;
}

int rtp_sender_init_srtp(rtp_sender_t sender, const srtp_policy_t *policy) {
    return srtp_create(&sender->srtp_ctx, policy);
}

int rtp_receiver_init_srtp(rtp_receiver_t sender, const srtp_policy_t *policy) {
    return srtp_create(&sender->srtp_ctx, policy);
}

rtp_sender_t rtp_sender_alloc() {
    return (rtp_sender_t) malloc(sizeof(rtp_sender_ctx_t));
}

rtp_receiver_t rtp_receiver_alloc() {
    return (rtp_receiver_t) malloc(sizeof(rtp_receiver_ctx_t));
}
